With the development of Internet technology, a great amount of data is present on the Internet. In particular, recently, cases where video data is uploaded or downloaded, or where video data is provided in real time using a streaming service have greatly increased. Further, video data services gradually occupy a larger part of even web services, such as various types of search portal websites, blogs, cafes, or mini-homepages. Furthermore, there are many cases where pieces of video data, such as video data related to broadcasts or movies, are provided over the Internet.
In particular, cases where original video data is edited or adapted by a plurality of users and is provided in a modified form on the web have also increased. Further, for example, a plurality of episodes appear as separate video data within a single drama series, and a piece of video data of one hour or longer in which a plurality of short music videos are compiled may be present. Furthermore, a case where part of a specific drama is included in video data edited by a user as a part of the video data may exist. If relations between pieces of video data, which are present to be modified or edited in various forms as above, can be detected, identical or similar pieces of video data present in various forms on the network may be conveniently searched for. Further, the copyrights management of the video data may also be conveniently performed. Furthermore, if mutual relations between pieces of video data that are present in various forms on the web, but have a predetermined common relation can be detected, it is possible to utilize the video data as advertisement data or as other pieces of additional data based on the mutual relations. However, a conventional video DB is limited in that it simply stores only information about individual pieces of video data without reflecting such mutual relations.